Metabolism in the hypothermically perfused kidney. Production and utilization of lactate and utilization of acetate in the dog kidney.

The mechanism for the high lactate production during hypothermic kidney perfusion has not been clarified previously. The metabolism of lactate and acetate was studied in 23 dog kidneys during continuous hypothermic perfusion. The perfusions were performed in a Gambro machine with a perfusate based on human serum albumin. With a perfusate containing fatty acid extracted albumin, which was almost free of fatty acids, the glucose uptake of the kidney was more pronounced than during perfusion with a fatty acid-rich perfusate. The high glucose uptake under this perfusion condition was associated with a lower lactate production and a higher glucose oxidation rate. In perfusions with a perfusate containing lactate at a concentration of 2.5 mmol/l a considerable lactate uptake of the kidney was shown. By isotope dilution technique the production and uptake rate of lactate was estimated at 4.4 and 8.0 mumol/g kidney and day in two experiments. The labeled lactate carbon was recovered in CO2, and glucose in the perfusate indicating a continuous oxidation and gluconeogenesis. Acetate was used by the kidney both for oxidation and for gluconeogenesis. Addition of acetate to the ordinary fatty acid-rich perfusate caused an enhanced lactate production from the perfused kidney. The results indicate that the high lactate production during hypothermic perfusion of kidneys is mainly dependent on a metabolic blockade at the level of pyruvate dehydrogenase.